A man was killed and two others injured in a shooting early Monday morning in the tunnel connecting Blue and Red line Jackson stops, according to the Chicago Police Department.

The shooting occurred just after 2 a.m. in the 200 block of South Dearborn Street, police said.

The man pronounced dead at the scene was shot in the chest and abdomen. Another was shot in the head and arm and was taken to Northwestern Memorial Hospital in critical condition.

The third victim was a 19-year-old woman shot in the lower back and taken to Northwestern Memorial Hospital. She was believed to be with the men but not a target of the attack, according to investigators.

Police said the shooter and two male victims knew each other and “had a prior dispute making this incident personal in nature.” 

“Efforts are underway to identify a person of interest and that individual will be questioned by detectives,” police spokesperson Anthony Guglielmi said in an email. He said more information will not be released until that time.

Red and Blue Line trains continued to run following the shooting but bypassed the Jackson stations as police investigated the scene.

No arrests have been made but Guglielmi tweeted investigators have “good leads on a person of interest.”

The attack is the third in a series of violent incidents on CTA train lines in less than two weeks.

 On Feb. 4, a musician was stabbed at the Jackson Red Line stop by a woman who said his music was giving her a headache. The following day, a man was shot at the UIC-Halsted Blue Line stop.